Helicopters are often stored with their blades in a stowed position to reduce the overall storage space needed for the helicopter or other aircraft and to protect the blades from impact damage caused by equipment or personnel working on the helicopter. The stowed position also protects the blades from potential damage during extreme weather conditions by moving the blades closer to the helicopter or aircraft body to reduce exposure of the blades to severe winds and/or debris. Blades of helicopters are often stowed by pivoting each of the blades at their root such that the blades are each positioned over the aft fuselage of the helicopter and are mechanically held relative to the fuselage. Stowing the blades of a helicopter is convenient for ship-board helicopters when stored in the busy and confined spaces of an aircraft carrier or during rough sea conditions. In addition, in the stowed condition, the helicopter does not take up as much storage space as a helicopter with fully extended blades and the blades are protected from equipment that may be moving about storage areas that could strike and damage the extended blades.
Referring to Fig. 1 a helicopter aft fuselage 3 having helicopter blades 1 rotated into the stowed condition and a prior art blade restraint system 2 that secures the stowed blades 1 to the helicopter fuselage 3 are shown. As was described above, the blades 1 are pivoted about their roots such that the blades 1 are positioned over the aft fuselage 3 in the stowed condition. The prior art blade restraint system 2 includes a relatively heavy and cumbersome steel and aluminum clamp associated with each blade 1, a pair of relatively heavy cylindrical metal support poles 5 associated with each clamp 4 and a relatively heavy steel fuselage support 6 that extends from a side of the fuselage 3 in a predetermined orientation. The prior art blade restraint system 2 includes over one hundred twenty-four (124) metallic parts in each clamp 4 alone and the metallic construction of the clamp 4, support poles 5 and fuselage support 6 is susceptible to corrosion of many types including galvanic and stress corrosion. The relatively complicated prior art blade restraint system 2 holds the blades 1 in the stowed condition by fixing the fuselage supports 6 in the predetermined orientation relative to the helicopter fuselage 3, mounting the poles 5 to the clamps 4, mounting the clamps 4 to the blades 1 and mounting the poles 5 to the fuselage support 6 in a predetermined order and orientation.
The prior art clamps 4, supports 6 and poles 5 are constructed of relatively heavy steel, aluminum or other metallic materials. The poles 5 each have a generally cylindrical cross-section and are removably mountable to both the fuselage supports 6 and the clamps 4. The fuselage supports 6 include metal dovetail fittings 6a into which a bottom of the poles 5 are removably insertable in a predetermined single orientation such that the predetermined poles 5 are associated with a predetermined blade 1 in a predetermined orientation and position. The poles 5 are pivotally mounted to each other at their top by a pole fitting 5a such that the poles 5 are pivotable between a deployed and a storage position. In the storage position, the cylindrical poles 5 are positioned adjacent to each other such that their longitudinal axes are generally parallel.
The clamps 4, poles 5 and support 6 are relatively large due to the distance between the fuselage support 6 and the blades 1 in the stowed condition and the typical loads that are supported by the clamps 4, poles 5 and support 6. Accordingly, the clamps 4, poles 5 and supports 6 are heavy and cumbersome for ground support personnel. Further, the multitude of parts that make up the prior art blade restraint system 2 increase the likelihood that individual parts may become lost, negatively impacting the use of the device. Lost parts in an aircraft environment is also disfavored because even small lost parts can severely damage the aircraft and, specifically, moving parts of the aircraft when blown about an area where the aircraft or helicopter are taking off. In addition, damage to the metallic parts of the prior art blade restraint system 2 is difficult to repair in a field environment and, specifically, if the poles 5 are bent or crushed, they are unable to be repaired in the field. The poles 5 are specifically subject to crushing damage because the poles 5 are separated during storage because of their cylindrical shape and their weight, which makes the poles 5 difficult to maneuver in a helicopter environment.
In operation, a ground support personnel member carries the cylindrical metal poles 5, steel and aluminum clamps 4 and fuselage support 6 to the fuselage 3. The fuselage support 6 is secured in a predetermined position and orientation to the aft fuselage 3 and the blades 1 are pivoted about their roots such that they are positioned over the aft fuselage 3. The ground support personnel member engages each of the heavy and cumbersome clamps 4 with a specific set of metal poles 5. A first clamp 4 and pair of poles 5 is lifted toward a predetermined blade 1 and the clamp 4 is positioned onto the blade 1 for mounting. The clamp 4 is then engaged with the predetermined blade 1 and the clamp 4, poles 5 and blade 1 are lifted such that a lower end of the poles 5 may be engaged with the fuselage support 6 at a predetermined location. The poles 5 are secured to the fuselage support 6 in the orientation shown in FIG. 1.
Due to the weight and size of the poles 5 and clamp 4, maneuvering the poles 5 and clamp 4 into and out of engagement with one of the blades 1 is difficult and cumbersome. In addition, lifting the weight of the poles 5, clamp 4 and part of the blade 1 to engage the poles 5 with the fuselage support 6 is difficult. The heavy and cumbersome prior art blade restraint system 2 is often dropped or mishandled by the ground support personnel and dropping the heavy clamp 4 with its sharp and exposed edges onto the ground around the helicopter or onto the helicopter itself tends to cause damage to the poles 5, clamp 4 and/or the helicopter itself. In addition, a predetermined set of poles 5 is associated with one blade 1 of the helicopter, which generally includes four blades 1, and each set of poles 5 must be positioned at a specific orientation on one of generally two fuselage supports 6. Accordingly, the prior art blade restraint system 2 must be engaged and disengaged with the helicopter in a specific order and must be correctly oriented or the system will not properly engage the blades 1.
To prepare the helicopter for flight, the poles 5 are disengaged from the helicopter such that the clamps 4 and poles 5 are suspended from the blades 1. The clamps 4 are released from the blades 1 and the clamps 4 and poles 5 are lowered onto the ground, which is a step that often results in mishandling of the clamp 4 and poles 5 combination and damage to the clamp 4, poles 5 or helicopter. Because of their size and weight, the poles 5 and/or clamps 4 are difficult for ground support personnel to maneuver and are often dropped onto the ground or into the helicopter fuselage 3 or blades 1, thereby damaging the blade restraint system 2, fuselage 3 and/or blades 1. The clamps 4 are disengaged from the poles 5 and the heavy poles 5, support 6 and the clamps 4 are removed by the ground support personnel member from the helicopter and placed into storage. In addition,due to the cylindrical shape of the poles 5, the poles 5 rest next to each other in a storage position and are relatively easy to damage by crushing if mishandled.